1. Field of the Invention
The present invention relates to a treatment solution for ink-jet recording, a water-based ink set for ink-jet recording, an ink jet recording method, and an ink jet recording apparatus.
2. Description of the Related Art
A treatment solution (process liquid), which is blended with an aggregating agent such as a polyvalent metal salt or the like for causing a colorant contained in a water-based ink to aggregate, is used in some cases before performing the ink jet recording by using the water-based ink in order to improve the optical density (OD value) of a recorded matter. The treatment solution is sometimes blended with diethylene glycol monobutyl ether (di-PB) or dipropylene glycol monopropyl ether (DPP) as a penetrant for adjusting the drying speed on a recording medium. The treatment solution, which contains the components as described above, is excellent in the drying performance on paper surface. The drying performance on paper surface means the easiness of drying brought about when the treatment solution is discharged onto the recording medium.
However, the conventional treatment solution involves a problem in relation to the discharge stability obtained when a head is maintained in an uncapped state. This problem arises such that when the head is maintained in the uncapped state, the treatment solution undergoes the increase in viscosity in a period of time shorter than a desired maintaining time and the discharge characteristic is deteriorated, although it is intended to maintain the stability of the discharge for a period of time as long as possible. In general, in the case of such a treatment solution, any compound, which originates from the material for forming an ink-jet recording apparatus, is eluted into the treatment solution in some cases. The material, which forms the ink-jet recording apparatus as described above, is exemplified, for example, by a rubber member and a member of organic material other than rubber material. The rubber member is exemplified, for example, by a wiper and a cap. The wiper wipes, for example, a nozzle surface of a discharge head for the treatment solution. The cap shuts off, for example, the nozzle surface from the external environment. If any compound, which originates from, for example, the rubber member, is eluted into the treatment solution, the compound is deposited in the treatment solution in some cases. If the compound is deposited, for example, it is feared that the nozzles of the discharge head for the treatment solution may be clogged-up.
On the other hand, in the case of a water-based ink set for ink jet recording in which the conventional treatment solution and the water-based ink are combined, the optical density (OD value) of a recorded matter is improved, and the strike-through (see-through) of the water-based ink is suppressed on the recording medium. However, in the case of the water-based ink set as described above, any unevenness arises on the recorded matter in some cases on account of the use of the treatment solution.